The present invention relates generally to the art of cutting, sorting, transporting and stacking paper webs or the like in sheet form in a continuous operation. More particularly, the present invention relates to an improvement in a sheet stacking mechanism for such a machine where the machine has the capability of cutting the web into a wide range of sheet sizes.
The invention was developed in connection with other improvements to the sheet cutting and stacking machines disclosed generally in applicant's prior U.S. Pat. Nos. 3,203,326 and 3,272,044, however, the invention herein is not limited to such an application. For instance, the stacking mechanism of the present invention could be used independently in any application requiring the stacking of sheets such as a printing press. However, as disclosed herein the continuous operation is performed at high speed, preferably on a single web of paper, and the final stacked sheets are sold under the registered trademark AccuTrim paper, marketed by the Assignee herein.
The invention is an improvement in the machines disclosed in U.S. Pat. Nos. 3,203,326 and 3,272,044, the disclosures of which are incorporated herein by reference. More particularly, the present invention comprises an improved sheet stacking mechanism for handling a wide range of sheet sizes.
The stacking mechanism is located at the off-loading end of a machine having a fixed height sheet delivery mechanism substantially as disclosed in the prior art. However, with the apparatus of the present invention, the stacked sheets can be more quickly and readily removed from the stacker than is possible with prior art systems, which produces concomitant increases in production efficiency. Further, the stacking mechanism of the present invention accomplishes its goals with less demand on the machine operator and with more automatic control than the systems of the prior art. For instance, the prior art machines require elevated platforms and walkways for tending, whereas with the machine of the present invention, all operator functions are performed from the operating floor level.
The following prior U.S. patents are exemplary of the known sheet stacking mechanisms: Nos.
1,863,465 PA1 1,942,172 (271-88) PA1 1,519,817 (112-10) PA1 2,700,947 (112-10)
In U.S. Pat. No. 1,519,817, there is disclosed a sheet delivery mechanism with means for automatically lowering the paper holding table as the sheets are piled thereon. However, the means is such that only an intermittent lowering action can be achieved. U.S. Pat. No. 1,863,465, discloses a sheet stacking mechanism which includes jogger devices wherein actuation of the joggers also provides for vertical positioning of the stack. However, the mechanism is comprised of a complicated gear train without any real control and without a readily useable system for stacking different length sheets, nor for easily removing the stacked sheets from the machine. U.S. Pat. No. 1,942,172 discloses yet another sheet stacking device which is designed to both jog the stacked sheets and adjust the height of the stack as additional sheets are delivered to the stack. Meanwhile, U.S. Pat. No. 2,700,947 illustrates a sheet stacking device which automatically lowers the stacking table to accomodate the successively increasing height of the stack of cut sheets. The apparatus disclosed therein utilizes a drive much like that preferred by applicant herein but without the different sheet length stacking capability of the present device and without the desired automatic control disclosed herein.